1. Field of the Invention
The present invention is related to a straw chopper for a combine and in particular to a straw chopper housing mounted to the combine for rotation about a transverse axis to move the straw chopper housing from a chopping position to a windrowing position.
2. Description of the Related Art
In a typical combine harvester, crop residue from the separator, also referred to as straw, is discharged from the hood structure at the rear of the combine. The straw is already somewhat reduced in size from the threshing and separating operations. If it is desired to reduce the size of the straw further, it is passed through a straw chopper. With current agricultural practices that eliminate or reduce tillage of the soil prior to planting, it is necessary to chop the straw into many small particles and then disperse the chopped straw over a wide area, generally equal to the width of the harvesting platform. As platforms have increased in width, it has been necessary to provide increasing width in the dispersion of straw at the rear of the combine.
Straw choppers have been used at the rear of the combine to chop the straw into small particles and to disperse the chopped straw over a wide area. The most common type of straw chopper consists of a transversely mounted flail rotor associated with a transverse array of fixed shear blades carried in a housing. The housing has an inlet opening and is supported beneath the combine hood to intercept the flow of straw from the separator. In some harvesting conditions, or to preserve longer straw for later collection, it is desired to return the straw to the ground in a narrow width windrow immediately beneath the combine hood without passing the straw through the chopper or widely dispersing the straw.
A straw chopper mounting for a combine is shown in patent 4,669,489 where a rear mounted straw chopper receives the straw from the straw walkers of the combine and discharges chopped straw rearwardly. The chopper is slidably supported on a pair of spaced apart, longitudinally oriented guide rails so that the chopper can be adjusted from a rearward chopping position to a forward windrowing position in which straw bypasses the chopper by dropping from the combine behind the chopper. Movement of the chopper on the guide rails is facilitated by attachment of a transverse shaft and sprocket assembly to the straw chopper housing. Teeth of the sprockets engage longitudinally spaced openings in the guide rails. Upon rotation of the shaft, the sprockets and guide rails cooperate in rack and pinion fashion to propel the chopper assembly along the rails while maintaining the chopper assembly in square alignment. The shaft is rotated by means of a wrench engaging flats on one end of the shaft.
Other straw choppers are mounted in a fixed position to the combine side sheets and use moving baffles or doors to direct the straw either into the chopper or directly to the ground for windrowing. With a fixed position chopper, the chopper restricts access to the rear of the combine for servicing or cleaning.